2.99 See Answer

Question: The SN2 reaction between a Grignard reagent

The SN2 reaction between a Grignard reagent and an epoxide works reasonably well when the epoxide is ethylene oxide. However, when the epoxide is substituted with groups that provide steric hindrance, a competing reaction can dominate, in which an allylic alcohol is produced. Propose a mechanism for this transformation and use the principles discussed in Section 7.11 to justify why the allylic alcohol would be the major product in this case below.
The SN2 reaction between a Grignard reagent and an epoxide works reasonably well when the epoxide is ethylene oxide. However, when the epoxide is substituted with groups that provide steric hindrance, a competing reaction can dominate, in which an allylic alcohol is produced. Propose a mechanism for this transformation and use the principles discussed in Section 7.11 to justify why the allylic alcohol would be the major product in this case below.





Transcribed Image Text:

OH но 1) EtMgBr Et 2) H,0 Major product Minor product



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> 99. For the following substitution reaction, which statement is FALSE? a. The process is bimolecular. b. Increasing the concentration of hydroxide will cause an increase in the rate of reaction. c. The use of a polar aprotic solvent will enhance the r

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> Choline is a compound involved in neurotransmission. The biosynthesis of choline involves the transfer of a methyl group from SAM. Draw a mechanism for this transformation: CH3 H,C N- OH -он SAM H,C-N- CH3

> Assign a systematic name for each of the following compounds: Br, Br (b) (c) (d) Br CI (e) (f) (h)

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> Predict the products for each of the following reactions: Excess HBr Excess HBr ? Excess HỊ ? ? Heat Нeat (a) (b) Heat yI? „O^E ? .O Excess HI Excess HBr Excess ? Heat Heat Heat (d) (e) (f)

> Show how you would use an alkoxymercuration-demercuration to prepare isopropyl propyl ether using propene as your only source of carbon and any other reagents of your choosing.

> How would you use an alkoxymercuration-demercuration to prepare dicyclopentyl ether using cyclopentene as your only source of carbon?

> Identify reagents that you could use to prepare each of the following ethers via an alkoxymercuration-demercuration: OEt (a) (b)

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> Propose a plausible mechanism for each of the following transformations: OH 1) MeMgBr 2) H,0 (a) 1) Excess MeMgBr 2) H20 но он (Б)

> Diethyl ether was commonly used as an anesthetic before its negative effects on the human nervous system were recognized. As part of a study to develop a method for predicting toxicity based on structure, the observed toxicity of a variety of dialkyl eth

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> Provide an IUPAC name for each of the following compounds: .CI (а) (b) (с) он OE! (d) (е)

> Suggest an efficient synthesis for the following transformation: CI H H.

> A variety of phenyl-substituted acetylenes (1a–d) were treated with HCl to give a mixture of E and Z isomers, as shown below a. As we saw in Problem 9.72, vinyl carbocations can form if they are stabilized by resonance. Draw the vinyl

> The two lowest energy conformations of pentane are the anti-anti and the anti-gauche forms, in terms of arrangements around the two central C−C bonds. A recent study analyzed the conformations of 3-heptyne as an “elongated” analogue of pentane, where a c

> Brevetoxin B (compound 2) is produced by Ptychodiscus brevis Davis, a marine organism responsible for red tides. Brevetoxin B is a potent neurotoxin, as a result of its ability to bind to sodium channels and force them to remain open. Its biological acti

> The compound 5,9,12,16-tetramethyleicosane was synthesized as part of a study of the male sex pheromone of a Brazilian bug that feeds on the leaves and fruit of tomato plants. The synthesis of this alkane was reported using compounds Aâ

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> The following procedure is part of a synthetic strategy for the enantioselective preparation of carbohydrates (Chapter 24): a. Under these strongly basic conditions (NaOH), the alcohol group is deprotonated to give an alkoxide ion, which can then funct

> Predict the products for each of the following: 1) Og 2) DMS 3) Excess LIAIH, 4) H0 ? 1) Os 2) DMS 3) Excess LIAIH, 4) H20 (a) (b) 1) EIMgBr 2) H,0 3) Na, Cr,0, H,SO4, H,0 4) EIMgBr ? (c) 1) LIAIH, 2) H,0 3) TsCI, pyridine ? (d) H 1) Hgo 2) Na, Cr,0,

> How many signals do you expect in the 1H NMR spectrum of each of the following compounds: OH Geraniol Isoprene (b) A precursor for natural rubber Isolated from roses (a) and used in perfumes

> Halogenation of alkynes with Cl2 or Br2 can generally be achieved with high yields, while halogenation of alkynes with 2 typically gives low yields. However, the following reaction is successfully completed with 2 in high yields (94%) to afford a potenti

> Salvinorin A, isolated from the Mexican plant Salvia divinorum, is known to bind with opioid receptors, thereby generating a powerful hallucinogenic effect. It has been suggested that salvinorin A may be useful in the treatment of drug addiction. Termina

> Treatment of one mole of dimethyl sulfate (CH3OSO3CH3) with two moles of sodium acetylide results in the formation of two moles of propyne as the major product: a. Draw the inorganic, ionic species that is generated as a by-product of this reaction and

> Reboxetine mesylate is used in the treatment of depression and is currently marketed as the racemate. The (S,S)-enantiomer of reboxetine is being evaluated for the treatment of neuropathic pain. The following synthetic scheme was part of the synthesis of

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> Propose an efficient synthesis for the following transformation: он + Enantiomer ÖH

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> Epoxides can be formed by treating α-haloketones with sodium borohydride. Propose a mechanism for formation of the following epoxide: NABH,

> Predict the product of the following reaction: Me 1) LIAID. ? Me 2) H,0

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> Draw a mechanism for each of the following reactions: он PEr он Br SOCI2 (a) Py (b) 1) Excess LiAIHe 2) H,0 CH,OH (c) он

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> Propose an efficient synthesis for each transformation. (a) OH (b) (c) CI (d) CI Xor (e) HO. OH OH (f) (h) + En (k) (0) OH (m) OH (n) LOH (о) HO. (p) 'CI он (9) CI H. он (r) OH HO, (s) + En (t) OH + En (u) OMe

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> When meso-2,3-epoxybutane is treated with aqueous sodium hydroxide, two products are obtained. Draw both products and describe their relationship.

> When the following chiral epoxide is treated with aqueous sodium hydroxide, only one product is obtained, and that product is achiral. Draw the product and explain why only one product is formed. NaOH H,0 ? Me 'Me

> Fill in the missing products below 1) Hg(OAc)2, EIOH Excess HỊ ? 2) NABH, Нeat ? RCO,H H-CEC: Na ? ? 1) NaSEt 2) H,0 ? HBr

> Fill in the missing reagents below. OH Me OH ? HO OEt ? |? ? Br OH HO, SMe Me OEt ? ? OMe DEt OH OH CN

> Predict the product and draw a mechanism for each of the following reactions: 1) LIAIH. 2) H,0 ? 1) NABH, 2) MEOH ? (a) (b)

> Using acetylene and ethylene oxide as your only sources of carbon atoms, propose a synthesis for each of the following compounds: HO он (а) (b)

> Predict the product for each of the following reaction sequences: 1) Hg(OAc), MeOH 2) NABH, ? (a) он 1) Hg(OAc)2. :? 2) NABH, (b)

> Propose a stepwise mechanism for the following transformation: Et Me Me 1) Excess EtMgBr Он 2) H,0 Et

> Draw the expected 1H NMR spectrum of the following compound:

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> What product do you expect when tetrahydrofuran is heated in the presence of excess HBr?

> Propose a plausible mechanism for each of the following transformations: OH 1) EtMgBr 2) I1,0 (a) 1) NaH OEt OH 2) EI (b) но 1) H-CEC: Na - 2) H,0 (c) OH MESH Mes (d) NaH (e) NAOH (ехcess) (f)

> Predict the products for each of the following: 1) RCO,H 2 MeMgBr 3) H,0 ? ia) 1) Hg(OAc), Meон 2) NABH, ? (b) ? 1) RCO,H ? OH 1) Na 2) NaSMe 3) Н,о 2) EICI (c) (d) 1) Na ? -HO- 2) (e) 3) H,0 ? CI 1) Mg, diethyl ether 2) A 3) H,0 (f)

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2.99

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